1. Field of the Invention
The present disclosure relates to a touch screen device in which to perform an input operation, a fingertip or the like of the user is pressed against the surface of a touch panel. More specifically, the present disclosure relates to a touch screen device that can provide tactile feedback to a user by vibrating a touch panel at the time of an input operation.
2. Description of the Related Art
When a touch screen device having a feedback mechanism that vibrates a touch panel at the time of input operation detects that a fingertip or the like of the user is pressed against any location or predetermined region on a panel surface (input operation surface) of the touch panel, a vibrating element such as a piezoelectric actuator is activated and vibrates the touch panel in a direction perpendicular to the panel surface. For example, when a fingertip or the like of the user is pressed against the panel surface of the touch panel, the device detects this and vibrates the touch panel. The user can learn from the vibration transmitted to the fingertip or the like that input operation is being surely performed.
Previously, there has been known a touch screen device that is made by providing vibrating elements on the outer edge of a rectangular touch panel, laminating and integrating this touch panel with a display panel with cushion members therebetween, and exposing a panel surface of the touch panel from an opening of an exterior case that houses this laminated body (see, for example, Japanese Unexamined Patent Application Publication No. 2006-227712). In the case of a touch screen device having such a configuration, the user can see an image on the display panel through the touch panel exposed in the opening. When the user presses their fingertip or the like against the panel surface of the touch panel, the touch panel detects the coordinate position of the fingertip or the like, and the vibrating elements are activated and minutely vibrates the touch panel in the thickness direction.
At that time, if the peripheral edge of the opening provided in the exterior case is in contact with or close to the panel surface of the touch panel, a vibrating noise is generated from the exterior case owing to the vibration of the touch panel. To address this, a space having predetermined dimensions is secured between the peripheral edge of the opening and the panel surface of the touch panel. The larger this space, the more effective it is to prevent vibration noise. However, a large space impairs the aesthetic appearance and makes it difficult to prevent the entry of a foreign substance. So, the space is minimized, and the dimensional accuracy and assembly accuracy of related components are controlled with a high degree of accuracy so that vibration noise is not generated.
If a through-hole for disposing operation buttons or the like is provided around the opening, or the length of one side of the opening increases along with the increase in size of the display panel, the vicinity of the peripheral edge of the opening of the exterior case becomes easily bendable. Therefore, even if the dimensional accuracy and assembly accuracy of related components are controlled with a high degree of accuracy, the vicinity of the peripheral edge of the opening is pressed backward and comes into contact with the vibrating touch panel when the user presses their fingertip against the peripheral region of the touch panel, and vibration noise is generated during the input operation. In particular, when this type of touch screen device is applied to an on-board electronic device, the user often performs an input operation using the lower edge of the opening as a finger guide without looking at the panel surface, and therefore, the above-described problem of generation of vibrating noise at the time of input operation becomes pronounced.